Wallace and Gromit have always taken their safety into their own hands, and in this episode of the science series they consider other inventors with the same philosophy. They tell the tale of 1940s Hollywood starlet Hedy Lamarr, who had a side-line in inventing, and who devised a radio-controlled 'secret-communication' system for steering torpedoes to help allied forces in the war, the technology of which is featured in all modern bluetooth systems.